Social media giant Facebook is coming home — at least one office of it is.

The social network, founded at Harvard by Mark Zuckerberg and others, announced this morning it will open an engineering office in Cambridge, its fifth official engineering office.

Officially called Facebook Boston, the site will be led by Ryan Mack, a Facebook engineer who worked on Timeline, one of Facebook’s recent signature products.

Facebook faces infrastructure and engineering challenges as they try to expand the company’s user base further.

“We’re going to need even more help to meet those new challenges, so we’ve decided to start building a new engineering team in Boston,” he said. In a release, Mack said the decision to come back to Boston and Cambridge was an easy one.

“Boston was an easy choice. The tech community here is world-class, from the incredible academic institutions to the vibrant startup ecosystem to the bevy of global companies who have teams here,” he said.

Mack said the team will be small, but will be hiring.

There has been a group of Facebook engineers in Boston for several years, bouncing around from coffee shops, a basement in Chinatown and co-working spaces, Mack said.

The departure of Facebook, which moved to California when Zuckerberg dropped out of Harvard, has been frequently cited by Massachusetts legislators and tech leaders as a prime example of the work that needs to be done by the state to entice the best start-ups to stay.

“This announcement reinforces our state’s standing as a place where innovators and technology companies want to be and positions us for the further growth of our innovation economy,” said State House Speaker Robert DeLeo, who sent a letter to Zuckerberg last year asking him to bring Facebook back to the Boston area.